In automobile construction, components are nowadays connected to one another ever more frequently by plastic forming, preferably by tensile-compressive forming, such as for example upset bulging, crimping or flanging. Compared with other joining methods, such as welding, connecting by plastic forming has the advantage for example of a lower cycle time in the production process and the avoidance of coating problems caused by the formation of scale. Particularly coating problems sometimes have to be laboriously reworked and are therefore undesired. The thin-walled components that are required for plastic forming, preferably tubes, for their part require auxiliary means or methods that further improve the quality of the connection between the components.